Waves and Warnings: teacher key

Earthquakes, grade 10 edition, written for 10th grade. Rock under the ground slips, and the shaking runs out in waves. Scientists measure the size, the place and the odds of an earthquake, but no one can say which day one will come.

Read the book. Print this page for the key.

Questions and answers

1. What does moment magnitude depend on?
   • The rigidity of the rock, the fault area and the slip distance (answer)
   • The number of people who felt the shaking
   • The depth of the nearest ocean
2. Why did the 1994 Bolivia quake cause no major damage even though it was felt as far as Toronto?
   • It was a small quake
   • It was so deep (answer)
   • It struck bedrock only
3. What does tsunami speed depend on?
   • How far the wave is from the source
   • The time of year
   • The depth of the ocean (answer)
4. Why can ShakeAlert give a warning before the damaging shaking arrives?
   • P-waves outrun S and surface waves, and data travel faster than seismic waves (answer)
   • It predicts the date of the quake years ahead
   • It stops the fault from slipping
5. In this passage, what does induce mean?
   • To cause something to happen (answer)
   • To measure the size of a quake
   • To warn people early

Words

• intensity: local shaking
• trench: deep ocean valley
• tsunami: giant ocean wave
• liquefaction: ground turning soupy
• epicenter: spot above start